nvmem: core: constify 'struct bin_attribute'

The sysfs core now allows instances of 'struct bin_attribute' to be
moved into read-only memory. Make use of that to protect them against
accidental or malicious modifications.

Also adapt the dynamic sysfs cell logic to handle the const attributes.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20241230143035.265518-2-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index d6494dfc20a7324bde6415776dcabbb0bfdd334b..fd09f1a6917fe8a43cc7b112d3611b1e000c7c16 100644 (file)
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -213,7 +213,7 @@ static struct attribute *nvmem_attrs[] = {
 };
 
 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
-                                  struct bin_attribute *attr, char *buf,
+                                  const struct bin_attribute *attr, char *buf,
                                   loff_t pos, size_t count)
 {
        struct device *dev;
@@ -246,7 +246,7 @@ static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
 }
 
 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
-                                   struct bin_attribute *attr, char *buf,
+                                   const struct bin_attribute *attr, char *buf,
                                    loff_t pos, size_t count)
 {
        struct device *dev;
@@ -340,7 +340,7 @@ static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry,
                                            const char *id, int index);
 
 static ssize_t nvmem_cell_attr_read(struct file *filp, struct kobject *kobj,
-                                   struct bin_attribute *attr, char *buf,
+                                   const struct bin_attribute *attr, char *buf,
                                    loff_t pos, size_t count)
 {
        struct nvmem_cell_entry *entry;
@@ -374,22 +374,22 @@ destroy_cell:
 }
 
 /* default read/write permissions */
-static struct bin_attribute bin_attr_rw_nvmem = {
+static const struct bin_attribute bin_attr_rw_nvmem = {
        .attr   = {
                .name   = "nvmem",
                .mode   = 0644,
        },
-       .read   = bin_attr_nvmem_read,
-       .write  = bin_attr_nvmem_write,
+       .read_new       = bin_attr_nvmem_read,
+       .write_new      = bin_attr_nvmem_write,
 };
 
-static struct bin_attribute *nvmem_bin_attributes[] = {
+static const struct bin_attribute *const nvmem_bin_attributes[] = {
        &bin_attr_rw_nvmem,
        NULL,
 };
 
 static const struct attribute_group nvmem_bin_group = {
-       .bin_attrs      = nvmem_bin_attributes,
+       .bin_attrs_new  = nvmem_bin_attributes,
        .attrs          = nvmem_attrs,
        .is_bin_visible = nvmem_bin_attr_is_visible,
        .bin_size       = nvmem_bin_attr_size,
@@ -401,12 +401,12 @@ static const struct attribute_group *nvmem_dev_groups[] = {
        NULL,
 };
 
-static struct bin_attribute bin_attr_nvmem_eeprom_compat = {
+static const struct bin_attribute bin_attr_nvmem_eeprom_compat = {
        .attr   = {
                .name   = "eeprom",
        },
-       .read   = bin_attr_nvmem_read,
-       .write  = bin_attr_nvmem_write,
+       .read_new       = bin_attr_nvmem_read,
+       .write_new      = bin_attr_nvmem_write,
 };
 
 /*
@@ -461,6 +461,7 @@ static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem)
                .name   = "cells",
        };
        struct nvmem_cell_entry *entry;
+       const struct bin_attribute **pattrs;
        struct bin_attribute *attrs;
        unsigned int ncells = 0, i = 0;
        int ret = 0;
@@ -472,9 +473,9 @@ static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem)
 
        /* Allocate an array of attributes with a sentinel */
        ncells = list_count_nodes(&nvmem->cells);
-       group.bin_attrs = devm_kcalloc(&nvmem->dev, ncells + 1,
-                                      sizeof(struct bin_attribute *), GFP_KERNEL);
-       if (!group.bin_attrs) {
+       pattrs = devm_kcalloc(&nvmem->dev, ncells + 1,
+                             sizeof(struct bin_attribute *), GFP_KERNEL);
+       if (!pattrs) {
                ret = -ENOMEM;
                goto unlock_mutex;
        }
@@ -494,17 +495,19 @@ static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem)
                                                    entry->bit_offset);
                attrs[i].attr.mode = 0444 & nvmem_bin_attr_get_umode(nvmem);
                attrs[i].size = entry->bytes;
-               attrs[i].read = &nvmem_cell_attr_read;
+               attrs[i].read_new = &nvmem_cell_attr_read;
                attrs[i].private = entry;
                if (!attrs[i].attr.name) {
                        ret = -ENOMEM;
                        goto unlock_mutex;
                }
 
-               group.bin_attrs[i] = &attrs[i];
+               pattrs[i] = &attrs[i];
                i++;
        }
 
+       group.bin_attrs_new = pattrs;
+
        ret = device_add_group(&nvmem->dev, &group);
        if (ret)
                goto unlock_mutex;